This invention relates to improvements in a control device for controlling a rectified output voltage from a battery charging AC generator to a predetermined magnitude for charging a storage battery.
Conventional control devices of the type referred to have included an initial excitation circuit through which an associated storage battery supplies a field current to a field coil of an AC generator involved to build up an AC voltage across the AC generator. The initial excitation circuit has included a parallel connected charge indication lamp and an initial excitation resistor so that, during a flow of field current through the circuit, the charge indication lamp is lighted, indicating that the storage battery is not charging. When a filament in that lamp has been broken because of long service, the entire field current flows through the parallel resistor to enable the initial excitation circuit. The use of such an initial excitation resistor has resulted in the necessity of employing a casing for that resistor, providing a space occupied thereby and electrically connecting the resistor to associated electric components. Therefore, the conventional control devices have been disadvantageous in that, in order to provide for the possibility of breaking of the filament in the charge indication lamp which might occur inherently even though with a small probability, complicated and expensive means have been required which rarely serve the intended purpose.
Accordingly, it is an object of the present invention to provide a new and improved control device for controlling a battery charging AC generator which does not include an initial excitation resistor such as has been previously required to be connected across a charge indication lamp.